The present invention relates to clustered arrangements of multiple data processing systems, and more particularly to data sharing, including byte file system data, in a clustered arrangement.
In today""s information technology industry, customers desire systems that have better performance and cost improvements over their current systems, while permitting continued use of their existing applications. High availability is also important given today""s rising mobile workforce and ability for global connectivity through the Internet. Current processing system designs for information technology applications must provide scalable, granular growth, and continuous application availability. Clustering technology, such as IBM Corporation""s S/390 Parallel Sysplex, has been developed to achieve these design needs.
A cluster arrangement links individual data processing systems in a manner that creates a single, powerful system, which can support numerous users simultaneously. A cluster offers high availability and excellent scalability. If one system/node in the cluster fails, the other systems in the cluster continue to run. FIG. 1 illustrates a cluster arrangement, e.g., a parallel sysplex system. Multiple systems 10, e.g., System 1 to System N, are included in the sysplex, where each system 10 has one or more computing processors 12 and memory with local caches 14. By way of example, the System/390 Parallel Sysplex from IBM Corporation, Armonk, N.Y., is an example of a set of S/390 systems connected together by a clustering technology. An instance of the operating system, OS/390, runs on each system of the sysplex. Each of the systems access DASD (direct access storage device) 20 that is shared among the systems. The clustered system support enables large business applications to be spread across the multiple systems with dynamic workload balancing, which yields a wide range of application capacity scaling and extremely high application availability across planned and unplanned outage of individual systems. The load-balancing and availability features of parallel sysplex result in an application running on one system at one point in time and then run on another system at another point in time. To help facilitate the activity, the systems 10 are each coupled to an external time reference component 16 and a coupling facility 18. Connections to DASD subsystems 20 are facilitated through a dynamic switch 22.
In addition to traditional transaction managers, database managers, and file systems for a multi-system arrangement, a byte file system is desirable in a cluster system. For example, the OS/390 operating system running on each system of the S/390 parallel sysplex includes a UNIX operating system environment for the deployment of UNIX applications. The UNIX file system, i.e., a byte file system, also referred to as an HFS (hierarchical file system), is provided in the base OS/390. However, current HFS implementations do not provide multi-system read/write data sharing. Thus, a need exists for an extension of the scope of an HFS from a single system to multiple systems, particularly, multiple systems arranged in a cluster or parallel sysplex arrangement.
Another challenge facing clustered arrangements is provision of direct access to DASD for shared files. Typically, large overhead is required for message sending of the file data between a file system instance on one system to a file system instance resident on other systems. Thus, for clustered environments, like the S/390 parallel sysplex, a need exists for the utilization of the shared DASD capability of the sysplex arrangement to directly access DASD resident shared files from multiple systems in order to reduce the overhead and increase the throughput of multi-system file sharing.
The present invention addresses such needs.
The present invention provides for system and method aspects for read/write data sharing of DASD (direct access storage device) data in a cluster of multiple data processing systems. In a method aspect, the method includes utilizing a first system as a managing system for file data modification of at least one file system, the at least one file system including a byte file system. The method further includes controlling access by at least one second system within the cluster of multiple system to data of the at least one file system through global token management, wherein concurrent, direct DASD read/write sharing of data of the at least one file system across the cluster of multiple systems occurs.
Through the present invention, the ability to directly read and write a file from multiple systems is effectively achieved. The shared DASD functions that permit access from multiple systems through the described software protocols/techniques provide the serialization for maintaining full integrity of the file systems across the multi-system data sharing environment. These and other advantages of the aspects of the present invention will be more fully understood in conjunction with the following detailed description and accompanying drawings.